But they work well.

[Nike] has teamed up with contact lens maker Bausch and Lomb to create performance-enhancing contact lenses called MaxSight. They're a tinted version of daily disposal lenses for athletes that reduce glare and improve visual acuity.

They block nearly all the sun's damaging UVA and UVB rays just like sunglasses, but their optics can also give athletic performance a boost.

"I think they're spectacular," says optometrist David McBride, who sells Maxsight at his clinic in Portland. He wears the grey-green version to improve his golf game, and estimates he has fit a dozen of his patients with MaxSight, most of whom have never worn contact lenses before. "I expect they will become very popular come spring."

The lenses come in amber for sports like baseball and tennis where the wearer must separate fast moving objects from the background, and grey-green for sports like golf, where the background environment is what’s visually important. Both colors filter out a significant amount of overall light, but they also sharpen and improve contrast, so they have a brightening effect, says Alan Reichow, who invented the lenses and is a sports vision consultant for Nike.

The amber lenses also turn the wearer's eye's an unsettling shade of red. But when Nike asked players if they'd like to create a version that created less of an evil eye, the answer was an overwhelming "no."